A technique for the synthesis of molecularly imprinted polymers (MIPs) in small scale (∼55 mg) coupled with direct in situ processing and batch rebinding evaluation is reported. The primary assessment is based on quantification by HPLC or UV absorbance measurement of the amount of template released from the polymer in a given solvent. This method allows a rapid screening of the parameters of importance to reach a desired level of binding affinity capacity and selectivity for a given target molecule. This was demonstrated for the triazine herbicide terbutylazine, where an initial screening was performed for the type of functional monomer used in the MIP preparation. Thus among the six functional monomers tested, methyl methacrylate, 4-vinylpyridine, and N-vinyl-α-pyrrolidone led to rapid and quantitative extraction whereas methacrylic acid and (trifluoromethyl)acrylic acid led to polymers that retained the template the most. After having established useful functional monomers, a secondary screening for selectivity was performed. In this, nonimprinted blank polymers were prepared and a normal batch rebinding evaluation was performed. The polymer showing the highest selectivity was the one prepared using methacrylic acid as functional monomer. This polymer was shown to strongly retain chlorotriazines including atrazine when a normal-scale batch of the polymer was evaluated in chromatography.

SummaryIn parallel to a long lasting search for universal multi-purpose sorbents, the area ofsohd phase extraction (SPE) is recently experiencing a rapid development of new lypes of tailor-made class specific or compound-specific sorbents which are designed to respond to the increasing demand for selectivily and efficiency in sample clean-up prior to quantification. An important issue here is the enrichment and clean-up of complex samples, such as environmental waters, sediments, biofluids and foodstuffs prior to detection .This because the analyte is often present in low concentration in a complex mixture of similarcompounds and therefore needs to be isolated and enriched in order to be detected by standard analytical techniques.The fact that molecularly imprinted polymers (MIPs) can in principle be prepared against any low molecular weight target molecule, can endure harsh working conditions and work in organic solvents makes them extremely attractive as class or compou nd-specific sorbents.This review critically discusses the application of the technology of molecular imprinting to solid phase extraction with examples of the different approaches (off-hne, on-line, coupled column), the different sorbent formats (cartridge, membrane, solid phase microextraction (SPME)) and the different protocols (selective adsorption, selective desorption)taken from the literature.The issues involved in the development of a new MISPE protocol (choice of template, functional monomer, crosshnker, evaluation of the phase and validation of the extraction protocol) and the problems associated with the bleeding of non-extracted template are also discussed.

An investigation of the material, chromatographic, thermodynamic, and kinetic properties of thermally treated (i.e., annealed) polymeric stationary phases imprinted with l-phenylalanine anilide (l-PA) was carried out. The imprinting procedure of the solid phase used in this study was the same as for the untreated imprinted stationary phase studied previously. However, after polymerization, these new stationary phases were treated at elevated temperatures (50, 120, 140, and 160 °C) for 24 h. The treatment at 120 and 140 °C led to a larger decrease in the retention of l-PA than that of d-PA. The polymer treated at 160 °C could no longer resolve the d,l-PA racemate. The heat treatments were accompanied by a decrease in swelling and an increase in density causing an increase in the density of the remaining active sites. The polymer treated at 120 °C was chosen for classical frontal analysis. The adsorption isotherms and the mass-transfer rate coefficients of d- and l-PA were derived from the experimental breakthrough curves. This study was carried out in the same temperature and concentration ranges as the previous one. A comparative discussion of the properties of the two polymeric molecular imprinted stationary phases is presented. The thermal treatment increases the saturation capacity of the packing material by one-third to one-half, reduces markedly the separation factor of the two enantiomers, and slightly accelerates their mass-transfer kinetics. There seems to be no interactions on the annealed polymer between the selective l-PA imprinted sites and the d-PA molecules.

A molecular imprinting procedure based on electrostatic and hydrogen bonding interactions was developed, resulting in polymers of high selectivity for complexing of L-phenylalanine anilide. The polymerization conditions were chosen in such a way that the formation of solution complexes between methacrylic acid (MAA) and the template (L-phenylalanine anilide) prior to polymerization would be favored. Thus, by increasing the ratio of MAA to the crosslinker (ethylene dimethacrylate, EDMA), polymers of a higher enantioselectivity and binding capacity were obtained. In the chromatographic mode, a high chiral separation factor (a = 3,4) was observed even for polymers prepared in presence of nearly 50 mol-Vo MAA in the monomer mixture. However, the use of polymers prepared by initiating at a lower temperature (40 instead of 60 "C) and polymers prepared using porogens of lower polarity (benzene instead of acetonitrile) only resulted in higher capacity factors (K). The association constant for the binding of Lphenylalanine anilide to the sites of an imprinted polymer as well as the number of accessible sites of the latter were estimated from a binding study using a batch and a chromatographic procedure.

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Key life science disciplines (e.g. diagnostics, proteomics, protein purification) rely on selective protein binders that serve the purpose of specifically capturing a protein in a complex matrix for either analytical or preparative use. [1,2] These binders are commonly of biological origin, for example, antibodies for protein fractionation or detection in proteomics or antibody-binding proteins (e.g. Protein A) for antibody capture in downstream processing. Common to most biologically derived protein binders are their lability, high cost, denaturation tendency, and intrinsically low binding capacity.Robust artificial protein binders in the form of molecularly imprinted polymers (MIPs) could potentially overcome these limitations, thus offering a step change in the above disciplines. [3] In spite of numerous reports that describe protein-imprinted hydrogels, advances towards generic and robust imprinting techniques have been slow. One reason is the need for employing a low cross-linking level in order to provide a mesh size of the network large enough for the protein to penetrate. The memory effects of these gels are thus easily erased, thereby preventing repeated use of the gels. Various forms of surface-imprinting techniques have been used with promising results to address this problem. [4] However, robust imprinting techniques that afford materials, which can compete with established bioaffinity media in terms of both affinity and capacity, are still lacking.By combining our previously developed hierarchical imprinting technique [5] for small molecules with protein imprinting we herein demonstrate a general technique ( Figure 1) to obtain protein-imprinted separation media that could potentially serve this purpose. As model proteins in this proof of concept study, the human blood plasma proteins, human serum albumin (HSA; 68 kDa, pI = 4.7), and immunoglobulin G (IgG; 150 kDa, pI % 9 for the monoclonal antibody in this study) [6,7] were chosen. As a first step, the proteins were physically immobilized on wide-pore silica (d p = 50 nm) at or close to their isoelectric points. This procedure is known to result in the formation of a strongly adsorbed monolayer with only minor loss of the native protein structure. [6] HSA was nearly quantitatively adsorbed under these conditions, whereas IgG showed a somewhat lower affinity ( Figure S1 in the Supporting Information). Saturation of HSA adsorption was reached at approximately 100 mg g À1 , which corresponds to a protein surface density of approximately 2 mg m À2 , consistent with a monolayer coverage. HSA-and IgG-modified silica templates were then prepared by adjusting the protein surface coverage of approximately 20 %-the submonolayer coverage being chosen in order to reduce surface protein-protein interactions.In order to benchmark the hierarchically imprinted polymers in comparison to reported bulk materials, we chose the common redox-initiated polymerization of methylenebisacrylamide (MBA) as cross-linking monomer (10 % w/w) and acrylamide (AAm) as functional mon...

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Ein guter Eindruck: Ein molekular geprägtes Polymer, das mithilfe einer stöchiometrischen Menge an Harnstoff‐basiertem Monomer gegen Penicillin G hergestellt wurde, zeigt eine hohe Affinität für das Templat (siehe Bild) und andere β‐Lactam‐Antibiotika, wie chromatographische Retentionsfaktoren in großen Puffermengen (90 %) belegen. Die Retentionswerte am nichtgeprägten Polymer waren unter denselben Bedingungen erheblich niedriger.